Inventory & Safety Stock Calculator
Calculate safety stock, reorder point, turnover days and suggested purchase quantity — and see how holding cost eats into your product profit. Supports Amazon FBA / Shopify modes. All local.
Results
Revenue Breakdown
Scenario Simulation
See how lead time / sales changes affect safety stock (logic to be implemented by IDE).
Scenario results will be shown here.
What Is Safety Stock?
Safety stock is extra inventory kept to cover demand spikes and supplier delays. Without it, you stock out and lose sales; with too much, you tie up cash and pay holding costs.
Simple vs Statistical Safety Stock
Simple mode: (max daily sales − avg daily sales) × max lead time. Statistical mode uses sales standard deviation and a service level (Z-score) for greater accuracy when you have historical data.
Reorder Point & Suggested Purchase
Reorder point = (avg daily sales × avg lead time) + safety stock. When inventory hits this level, reorder. Suggested purchase adjusts for on-hand and in-transit stock to avoid double-ordering.
Inventory Holding Cost Eats Profit
Holding inventory costs 20–30% of product value per year (capital, storage, insurance, obsolescence). This calculator links holding cost to your gross profit so you see the real cost of overstocking — something most calculators miss.
Amazon FBA Inventory Notes
FBA sellers face long-term storage fees and IPI (Inventory Performance Index) pressure. Keep turnover healthy and avoid slow-moving stock.